Magnetic field sensors measure magnetic flux and/or the strength and direction of a magnetic field. Magnetic field sensors can be used in many applications, including scientific, navigational and industrial applications. Magnetic field sensors use several types of sensing technologies, including magneto-resistive (XMR) sensing technologies and Hall effect sensing technologies. The XMR sensing technologies measure electrical resistance as a function of the applied or ambient magnetic field. The Hall effect sensing technologies convert the energy stored in a magnetic field to an electrical signal by developing a voltage between the two edges of a current-carrying conductor whose faces are perpendicular to the magnetic field.
Often, XMR sensors include a supporting magnet and one or more XMR sensing elements for measuring a magnetic field. The supporting magnet and the XMR sensing elements are in a fixed position relative to each other. The XMR sensing elements do not usually operate in their saturation range and the supporting magnet provides a back bias magnetic field that is superimposed on the XMR sensing elements to stabilize the transfer characteristic of the XMR sensing elements. Changes in an applied magnetic field produce changes in the resistance of the XMR sensing elements. XMR sensing elements include anisotropic magneto-resistive (AMR) sensing elements, giant magneto-resistive (GMR) sensing elements, tunneling magneto-resistive (TMR) sensing elements, and colossal magneto-resistive (CMR) sensing elements.
Usually, in Hall effect sensors a constant current is provided to a Hall element or plate and a magnetic field is applied perpendicular to the current flowing through the Hall plate. Charge carriers in the Hall plate are deflected due to the Lorentz force to create a Hall voltage that is perpendicular to both the magnetic field and the current flow. This Hall voltage can be measured and is directly proportional to the magnetic field.
In some current sensors, a magnetic field sensor is positioned next to a conductor carrying a current. The magnetic field sensor senses the magnetic field generated by the current and measures the current. The strength of the magnetic field depends on the distance from the conductor, such that the strength of the magnetic field decreases with larger distances. To accurately measure the current, the magnetic field sensor is precisely positioned relative to the conductor. However, precisely positioning the magnetic field sensor relative to the conductor can be expensive and adds cost to the current sensor.
In other current sensors, a magnetic field guide, such as a ferromagnetic core, concentrates the magnetic field in an air gap. The magnetic field sensor is positioned in the air gap to sense the magnetic field and measure the current. In this situation, the position of the magnetic field sensor in the air gap is not critical. However, the magnetic field guide can be expensive and adds cost to the current sensor.
For these and other reasons there is a need for the present invention.